[Hablemos de ruminates n°1] Soluciones Syva: vaccination is meaningful against Epizootic Haemorrhagic Disease.

We are starting a new year and one of the aims of cattle producers will surely be to avoid the consequences of EHD as far as possible. After two years of circulating in southern Europe, cattle producers have an effective tool for this new season of activity: vaccination. Therefore, control of the disease is much closer, with four basic objectives:

1. Ensuring protection for the next period of activity. It is not only important to have the vaccine available, but also to administer it at the right time. February to May is the most suitable vaccination window.
2. Avoiding immunosuppression caused by EHE. Over the past two years, we have seen that a large part of the pathology associated with the disease is caused by the action of the virus on the immune system.
3. Avoiding sub-clinical carrier animals. One of the key aspects in the spread of vector-borne diseases caused by orbiviruses is the existence of viremic animals over a long period of time. Vaccination not only prevents the development of clinical signs, but also slows down the progression of the disease in a territory by reducing viraemia in vaccinated herds.
4. Facilitating animal movements. Movement restriction is one of the standard measures to control the spread of any virus, but especially for orbiviruses such as BT and EHD. Therefore, vaccination of susceptible animals would facilitate such movements, avoiding the spread through viraemic cattle.

The good news is that a new EHE vaccine based on subunit technology is now available for cattle producers, which will allow us to consider a ‘marker’ (DIVA) strategy for disease control. SYVAC^® EH Marker is the first vaccine on the market with recombinant technology against a disease caused by an orbivirus. This vaccine guarantees immunity after the basic schedule of application, which results in a significant reduction in viraemia and clinical signs, with the option of differentiating animals infected by field virus, as it is a DIVA (Differentiating Infected from Vaccinated Animals) vaccine. In general, DIVA technology involves removing one or more antigens present in the field circulating agent strain (deletion mutants) from the vaccine. Alternatively, subunit vaccines can be used that also lack these particular antigens. If the antigens are not present in the vaccine, the detection of Ac against these antigens implies a natural infection. An appropriate screening technique, such as an enzyme-linked immunosorbent assay (ELISA), must be available to test for the presence or absence of the antigen concerned. Ideally, DIVA vaccines make it possible to eradicate a disease while continuing mass vaccination programmes. This newly available tool will allow meaningful vaccination to effectively control EHD in Europe.